The invention relates to a size reduction device, which is used in particular for the (preliminary) size reduction of materials to be pumped, for example for the size reduction of materials which are transported by means of an eccentric screw pump or suchlike. Such size reduction devices are used for example in biogas installations, sewage treatment plants etc., in order to perform a preliminary size reduction of coarse components in waste water or suchlike to a pumpable size.
DE 3782387 T2 describes a device for the size reduction of solid waste material. The solid waste material is introduced into the intermediate space of counter-rotating, intermeshed cutting elements. In particular, they are cutting discs with the radially projecting cutting teeth. The solid material is preferably conveyed with a liquid through the counter-rotating arrangement of cutting elements. The document also describes guide rails, which extend parallel to the flow direction of the liquid and comprise a plurality of fingers arranged in parallel, between which slots are constituted. The spacing between the fingers is so small that the flow passage arising between them prevents the passage of non-size-reduced waste material, but permits the passage of small particles of the solid waste with the through-flowing liquid. The flow-rate of the liquid is thus increased and at the same time the size reduction effect is increased.
U.S. Pat. No. 5,160,095 describes a size reduction device for solids or for solids suspended in solution. The latter comprises two stacks of counter-rotating cutting discs, which preferably comprised teeth as cutting means. The two stacks of cutting discs are disposed between two side rails. Each of the side rails comprises a plurality of ribs, recesses being constituted in each case between the ribs. The ribs and recesses are disposed at an angle with respect to the planes of the cutting discs, so that two or more cutting discs run past each rib. In particular, the teeth of the at least two cutting discs are positioned so close to the respective rib that good size reduction of each solid that is conveyed by liquid through the recesses between the ribs is achieved. In particular, the maximum size of the solids passing through can be precisely controlled with the arrangement without a reduction in the flow velocity.
The problem of the invention consists in achieving a particularly uniform size reduction of solid particles that is improved compared to the prior art in order to protect following devices, wherein in particular no larger particles are allowed to pass through the size reduction device without undergoing size reduction.
The aforementioned problem is solved by a size reduction device and a method for the size reduction of solid particles in accordance with the invention.